ARM: 5725/2: U300 switch MMCI to use regulator

This switches the U300 over from using a custom translate_vdd
function (which was just flipping blind bits in the hardware)
to using the regulator that actually controls the MMC voltage.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>